In recent years, the need to evaluate the credibility of clinical assay has led to the development of ISO 15189 and the Guide to the Expression of Uncertainty in Measurement (GUM), creating the movement toward evaluation of the quality of inspection rooms and the precision of measurement results. In April 2008, the disease-specific health checkup program called “specific health checkup” was started based on studies of metabolic syndrome, with the ultimate goal of preventing lifestyle-related diseases such as diabetes and cardiovascular diseases. The program is designed to provide guidance on diet and lifestyle to those who exceed certain diagnostic criteria, but the guidance requires follow-ups, meaning that it has to be followed by several diagnoses. This means that if values measured during the diagnoses vary greatly from day to day or from institution to institution, it is difficult to relay on such fluctuating values to offer guidance. Thus, the same constant values have to be obtained at any testing institution, and more precise measurement is now needed. As for analytical reagents, a particular reagent has to be used for a particular analysis method, and reagent manufacturers are now obliged to disclose reagent-by-reagent uncertainties that are necessary for value calibration. Uncertainties are also required to be disclosed on an analyzer-by-analyzer basis. Non-Patent Documents 1 to 3 discuss such uncertainties.
Daily use of an automatic analyzer results in reduced lifetime of its lamp and wear of its dispenser syringe, which consequently increases uncertainties. Measured values may fluctuate also when the lamp or the syringe is replaced, due to a change in absorbance and the like. As for the lamp, syringe, and other consumable components, a commonly adopted approach is to keep track of the duration of use and replace those when they are overdue.